崩岗土壤液塑限的离子特异性效应

Specific ion effects on liquid and plastic limits in soil of collapsing gully wall

为探究崩岗土壤液塑限的离子特异性效应,选取福建省长汀县河田镇一处稳定型崩岗的3个土层土壤(红土层、砂土层和碎屑层)为研究对象,用液塑限联合测定仪对不同离子(Li^(+)、Na^(+)和K^(+))盐溶液交换处理后的土壤液塑限进行分析。结果表明,红土层的土壤塑限、液限和塑性指数均显著高于砂土层和碎屑层(P<0.05)。土壤塑限和液限均与土壤黏粒含量、有机质含量、阳离子交换量以及高岭石含量呈正相关关系,其中,土壤塑限与黏粒含量和阳离子交换量呈显著正相关关系(P<0.05)。K^(+)交换处理后,红土层土壤塑限、液限和塑性指数比Li^(+)交换处理分别高5.80%、9.53%和12.99%,比Na^(+)交换处理分别高3.50%、9.77%和15.86%;K^(+)交换处理后,砂土层土壤塑限、液限和塑性指数比Li^(+)交换处理分别高7.22%、6.69%和6.83%,比Na^(+)交换处理分别高4.33%、5.27%和7.32%;而不同离子对碎屑层土壤液塑限的影响不显著。不同离子对同一土层土壤液塑限的影响不同,K^(+)交换处理后红土层、砂土层的土壤液塑限总体高于Li^(+)和Na^(+)交换处理,即较Li^(+)和Na^(+)而言,K^(+)可提高崩岗土壤液塑限。

Liquid and plastic limits are important parameters of soil hydraulic properties and are important in the research of collapsing gullies.To investigate the specific ion effects on the liquid and plastic limits of collapsing gullies,soil samples from three soil layers in a soil profile(red soil layer,sandy soil layer,and detritus layer)of a stable collapsing gully located in Hetian Town of Changting County,Fujian Province,were collected and exchanged with three kinds of electrolyte solutions(Li^(+),Na^(+),and K^(+))to analyze the liquid and plastic limits.The main results were as follows:the red soil layer had the highest plastic limit,liquid limit,and plasticity index,followed by the sandy soil and detritus layers(P<0.05).Correlation analysis showed that the clay content,organic matter content,cation exchange capacity,and kaolinite content were positively correlated with the plastic and liquid limits(P<0.05).Clay and organic matter contents were significantly positively correlated with the plastic limit.The plastic limit,liquid limit,and plasticity index of the red soil layer exchanged with K^(+)were 5.80%,9.53%,and 12.99%higher than those exchanged with Li^(+),and 3.50%,9.77%,and 15.86%higher than those exchanged with Na^(+),respectively.The plastic limit,liquid limit,and plasticity index of the sandy soil layer exchanged with K^(+)were 7.22%,6.69%,and 6.83%higher than those exchanged with Li^(+),and 4.33%,5.27%,and 7.32%higher than those exchanged with Na^(+),respectively.However,the liquid and plastic limits of the detritus layers did not differ significantly.The liquid and plastic limits of the red and sandy soil layers exchanged for K^(+)were significantly higher than those exchanged for Li^(+)and Na^(+).Therefore,compared with Li^(+)and Na^(+),K^(+)could increase the liquid and plastic limits of collapsing gullies.